Abstract
In this paper an alternative J2 material model with isotropic hardening for finite-strain elastoplastic analyses is presented. The model is based on a new nonlinear continuum mechanical theory of finite deformations of elastoplastic media which allows us to describe the plastic flow in terms of various instances of the yield surface and corresponding stress measures in the initial and current configurations of the body. The approach also allows us to develop thermodynamically consistent material models in every respect. Consequently, the models not only do comply with the principles of material modelling, but also use constitutive equations, evolution equations and even ‘normality rules’ during return mapping which can be expressed in terms of power conjugate stress and strain measures or their objective rates. Therefore, such models and the results of the analyses employing them no longer depend on the description and the particularities of the material model formulation. Here we briefly present an improved version of our former material model capable of modelling ductile-to brittle failure mode transition and demonstrate the model in a numerical example using a fully coupled thermal-structural analysis.
Highlights
Modelling materials within the framework of finite-strain thermoelastoplasticity represents a challenging task in computational mechanics
The related material models use an additive decomposition of a strain rate tensor into an elastic part, a plastic part and a thermal part and are based on a hypoelastic stress-strain relationship while utilizing the nonlinear continuum mechanical theory of elastic media to describe the plastic behaviour of the material [2, 11,12,13,14,15,16]
The related material models use a multiplicative split of a deformation gradient into an elastic part, a plastic part and the thermal part, the classical flow plasticity models from small-strain elastoplasticity while utilizing the nonlinear continuum mechanical theory of elastic media to describe the plastic behaviour of the material [2, 3, 17,18,19,20,21,22,23]
Summary
Modelling materials within the framework of finite-strain thermoelastoplasticity represents a challenging task in computational mechanics. The related material models use a multiplicative split of a deformation gradient into an elastic part, a plastic part and the thermal part, the classical flow plasticity models from small-strain elastoplasticity while utilizing the nonlinear continuum mechanical theory of elastic media to describe the plastic behaviour of the material [2, 3, 17,18,19,20,21,22,23]. Our ongoing research has shown, that both types of the aforementioned theories are just variants of our modified nonlinear continuum theory of finite deformations of elastoplastic media, using an additive decomposition of the displacement field into an elastic part, a plastic part and a thermal part, which describes the plastic flow in terms of various instances of a yield surface and stress measures in the initial or current configuration of the body. We briefly present a modified version of our former material model capable of imitating ductile-to brittle failure mode transition and demonstrate the model in a numerical example using a fully coupled thermal-structural analysis
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